That big gap is the MFT zone - on a freshly formatted NTFS volume the first 1/8 (12.5%) is reserved for the 'housekeeping', actual file data is written past that area (i.e. starting at 1/8 of the volume).
When the drive fills up the file metadata (name / time stamps / access rights) is added to the MFT and the actual file data is written to the 'upper' 87.5% of the volume. When that space is used up file data is also placed in the MFT zone, almost inevitably creating MFT fragmentation (thus the recommendation to never fill a NTFS volume to more than about 85% of its capacity).
Defragmenters tend to have their own view of 'proper' file data placement, so their use may change the layout a bit. Also, converting a FAT volume to NTFS will probably result in a layout similar to your screenshot.